1. Field of the Invention
The present invention relates to an electronic cartridge, which contains components that can thermally expand relative to each other.
2. Background Information
Integrated circuits are typically assembled into a package that is soldered to a printed circuit board. Historically, manufacturers of integrated circuits such as microprocessors have sold integrated circuit packages to entities that mount the packages to a motherboard. The motherboard is typically incorporated into a larger system such as a personal computer.
The integrated circuit packages are typically soldered to the motherboard. The solder process requires capital equipment such as wave solder tables, etc. Additionally, the solder must be reflowed to upgrade or replace the integrated circuit package that is mounted to the board. Reflowing the solder can degrade the integrity of the motherboard and the solder joints which couple other components to the board. It would be desirable to incorporate the integrated circuit packages into a cartridge that can be plugged into a motherboard so that the customer of the integrated circuit does not have to solder the package.
It would be desirable if such a cartridge could be plugged into the circuit board by a consumer, so that the end user can upgrade a system such as a personal computer. Such a cartridge would preferably have a cover to prevent contact between the end user and the integrated circuit packages. The cover may also improve the appearance of the product.
Integrated circuits generate heat which must be removed to insure that the junction temperatures of the circuits operate below threshold levels. The heat primarily flows into the ambient through the integrated circuit packages. The packages are typically constructed from a dielectric material which has a relatively low coefficient of thermal conductivity. The low coefficient creates a relatively high thermal impedance across the package. The high thermal impedance increases the junction temperatures of the circuit.
Some packages incorporate a metal lid to reduce the thermal impedance from the integrated circuit to the ambient. A thermal element such as a heat sink may be coupled to the lid to further increase the thermal efficiency of the assembly. It would be desirable to provide a cartridge that has both a thermal element and a protective cover which are coupled to a printed circuit board which supports one or more integrated circuit packages.
Electronic assemblies are frequently exposed to environments which have varying ambient temperatures. Changes in temperature will cause the assembly to expand or contract. Different components of an electronic assembly may have different rates of thermal expansion. The different rates of thermal expansion may create stresses in the assembly. It would be desirable to provide a cartridge which allowed different components of the assembly to expand and contract relative to each other.